How to Troubleshoot and Fix iPhone X Touch not Working Board Level Repair


Is your iPhone X touchscreen not responsive, slow to respond or not working in some ways? Most of the times, touch screen problems are caused by software glitches and bugs which Apple always takes care of with their regular iOS updates, but if this is not the case with your device, you would probably need to dig deeper into. In this article, we show the troubleshooting and repairing for iPhone X when touch not working. We hope you enjoy our sharing.


Step 1. Diagnosis

1. Install and Test

Install and test the iPhone X, the touchscreen appears fine but without touch function, so we move to motherboard troubleshooting after ruling out the possibility of screen assembly defects. 

2. Motherboard Troubleshooting

Measuring the touch connector resistance via multimeter. In this case, the touch connector pin J5800-24 was measured excessive resistance (normal value:330)

3. Circuit Analysis

The touch connector pin J5800-24 work as AP_TO_TOUCH_BSYNC_CONN signal, which is sent out from the CPU, via the top main board and the inductor FL5847. Therefore, A. CPU damage; B. poor soldering on the top main board; C. inductor damage can lead to abnormal resistance, in our case, the open circuit from connector pin J5800-24.



Step 2.CPU Troubleshooting

Measure the marked circuit according to circuit diagram, the resistance is normal, so we confirm the “no touch issue” is due to motherboard poor soldering.


Step 3. Reballing

Reballing motherboard and measure the motherboard again before installation to make sure it works well.

Last, install the motherboard, and then we can see the touch functionality works well, case closed.


Please refer to below detailed video:

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Tools & Materials used in this video:

Solder flux ×1;

Soldering iron ×1;

Hot air gun ×1;

Microscope ×1;

Multimeter ×1;

Tweezer ×1;

Solder paste ×1;

Rosin ×1;

PCB cleaner ×1;

Cleanroom wipes ×1;

Desoldering braid/solder wick ×1;

Hard disk programmer ×1;

Soldering net ×1;

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